Belt



D. F. MORGAN Feb. 1, 193s.

BELT

Original Filed Sept. 12. 1955 ramas rsh. i, 193s aromas l ,man

PATENT' '1T FFIC BMT noord Company, of Illinois r'. Marsan, oak Park,nl., mmm-'tn Chicago, lll., a corporation i continuation or application'serial No. 40,275,

September 12, 1935.

This application February 2l, 1936, Serial No.` 65,096

dclaims.

construction as to provide for an increased trac-A 5 tive eort andlflexibility with a resulting increased driving emciency andprolongation of belt life. 4

Heretofore, it was found that where flat belts are employed with crownedpulleys, the point of l greatest tension on the belt is at the highestportion of the pulley crown, because of the greater diameter of thepulley at this point.I The most eifecti've driving is done at this highpoint and its adjacent surfaces while the traction is lower l andthedriving emciency less at the outer portions .of the belt and pulley.This uneven traction ls-due to the stiffness of the belt and its in-'ability to adapt itself to the contour of the crowned pulley during thedriving operation.

This stiffness is increased as the speed of the belt progresses, theouter portions of the belt away from the high point of thel crowntending to assume a raised position out of contact with the lowerportions of the crown, therebyv reducing the driving emciency andputting the greater burden of the pulling load upon the central portionof the belt which is in contact with the surface of the high portion ofthe pulley crown.

Another factor reducing the tractive eiliciency 80 of the averagebelt onboth crowned and straight pulleys is the formation of an air cushionbetween the pulley and belt.C As the belt moves at normal operatingspeeds, a layer of air adjacent its pulley contacting surfaceis carriedalong a5 and compressed between the pulley andthe belt, forming an aircushion upon which the belt rides up `out of contact with the pulley.As'the speed of the driving pulley is increased, an increasing amount ofair intervenes between the belt and 40 the pulley, until a point isreached when thebelt slips ofi. 'Ihls latter disadvantage is alimitation on the amount 'of power that vcan be transmitted and also onthe rate of speed at which such belts may be safely driven.

Therefore, it is an object of my invention to provide a belt having asuperior quality of traction.

Another object is the provision of a belt having w lateral andlongitudinal flexibility enabling the belt to closely adapt itself tothe contour of a crowned pulley.

A further object is the provision of 'a belt having the ability toprevent the formation of an u intervening air cushion between the beltand (Cl. 'I4-232) the pulley, thereby increasing the ability of the beltto cling to the pulley surfaces.

A still further object is the provision of a belt having a maximumexibility and the ability to prevent the formation of an air cushionbetween the belt and the pulley so as to enable it to closely adhere tothe pulley surface throughout being had to the accompanying drawing in.

which:

Figure 1 is a perspective view of a portion of a belt embodying myinvention;

Fig. 2 is an enlarged lateral cross-section through a portion of. thebelt;

Fig. 3 is a diagrammatic sectional view of the belt; s

Fig. 4 is a sectional view through ythe belt and a crowned pulley whilein driving relationship;

Fig. 5 is an enlarged sectional view of a grooved portion of the belt indriving position on a portion of a crowned pulley.

This application is a continuation of my copending application forUnited States Letters Patent for Belts, Serial Number 40,275, ledSeptember l2, 1935.

Referring to the drawing, there is illustrated my improved belt I0 whichis comprised of a plurality of fabric webs and cords held together by acoating of rubber material in which they are embedded. Moreparticularly, the belt I0 has a ply or webof fabric I I which issubstantially the width of the completed belt end which is coated withan elastic bonding material or rubber solution I3. Extending lengthwiseof the ply il and adhesively amxed thereto are a plurality ofsubstantially inextensible cords I2v which are arranged in spaced groupstransversely of the ply, the spaces between the groups beingsubstantially less .than the width of the groups. 'I'hese groups arealso maintainedas units by the bonding material I3. An outer fabric plyor web I 4, also coated with the bonding material, is provided in adimension of slightlymore than twice "the width of the finished belt sothat it can be wrapped around the web Il and the cords I2 to encloseandv protect the same from injurious contacts and substances encountered-in certain industrial fields. LAnother fabric .web i5. alsocoated withthe rubber material, is disposed as a seal upon the surfaces of the edgeportions i4 of the web Il which have been folded into abutting relationover the cords i2. These above elements are vulcanized into a permanentunion in a mold which depresses the'web Il, the edges IIb of the web i4,the web i5. and the bonding material to form a plurality of grooves i8extending lengthwise of the belt and parallel to the cords in theportions of the upper surface |4 between the spaced groups of cords. Thelower surface i4l of the ply il, however, is formed flat.

In Fig. 4, there is illustrated my improved belt I in driving positionon a crowned pulley i1,

althOdgh it must be understood that the belty I0 is applicable withequal efficiency to other types of pulleys. As constructed, the beltpossesses a limited amount of elasticity that is sufficient to allow thebelt to be stretched into operable position over the driving and drivenpulleys with a reserve amount of elasticity remaining in the same toallow for any furtherA stretch encountered during operation. Theaforedescribed belt structure is designed for a maximum of tractiveemciency. In operation, it is preferably the lowstretched to a greaterdegree because of theer surface il* of lthe belt which is in drivingcontact'with the pulley l1.

,Since a crow'ned pulley has its greatest diameter at the highest pointI8 of the crown, it is obvious that the greatest stretch of the beltoccurs at its central portion causing the two central groups of cords tostretch longitudinally to 'a greater extent than the outer cord groupsadjacent the edges of the pulley. 'I'hese outer cord groups away fromthe pulley crown remainsubstantially unaffected by the stretch of thecentral cord groups, and are able to closely adhere' to those surfacesof the pulley where the diameter is reduced. 'I'his ability of the beltto readily adapt itself to the contour of the crowned pulley I1 is duetoits great-lateral and longitudinal ilexibility.' By providing laterallyspaced groups of substantially inextensible cords and by providinggrooves in the upper surface of the belt between the cord groups. theeffect secured is that of a plurality of individual belts of differentlengths adapted to the various diameters of a crowned pulley althoughthe belt is a strong unitary structure. 'I'he portions of the beltbetween the cord groups being substantially more elastic and of lessersection allow'the cord groups to move ,longitudinally relatively to eachother and also permit great lateral exing which would be reduced toaminimum were the cords extended throughout the width of the belt. Thus,the belt may be curved laterally to adapt itself to the crown contour sothat the outer belt portions willclosely adhere to the -outer pulleysurfaces without being raised out of engagement therefrom when thecentral portions of the belt are greater pulley diameter at their pointsof tact.

The tractive efficiency of the belt is further increased because of theability of the belt to prevent the formation of an undesirable air layeror cushion which tends to form between the belt and the pulley. As thebelt I0 is bent around v' -the pulley under driving tension. arelatively shalface, the grooves I 8 thus reversing themselves. Theformation of these grooves 20 is due, perhaps, to the coaction of twoforces. As the belt contacts the pulley under driving tension. therelatively inextensible cords l2 in groups squeeze down on the softercushioned portions formed by the two plies Il and. Il* embedded in therubber solution I8, these plies expanding laterally in both directionsto a limited extent. with the result that a buckling upwardly oi' thebelt portions between the groups of cords occurs. The

buckling is upwards because of the unyielding4 surface of the pulley andbecause the relatively elastic portions between the cord groups areunder a relatively lesser degree of tension. A second factor which mayalso cause the formation of the grooves 20 is the stretching of theupper ply I 4e. In riding around the pulley, the upper ply I4 isstretched to such an extent that the portions forming the grooves I 6are pulled up slight-- ly, thereby reducing the depth of the grooves I6and pulling up the other two plies which are adhesiveLv united to theunder surface of the ply I at a plurality of points. It is to beunderstood that the two above factors are merely theories as toformation of the grooves, but the fact remains that whatever may bethecause for formation, are created as the belt comes into contact withtheupulley and is curved about its surface. 'I'hese shallow groovedportions are the only points of the pulley-contacting surface whichmaintain their original unworn appearance after a long period ofoperation.

'Ihe grooves 20 prevent the formation of the undesirable air layerapparently for the following reason: As the cords I2 squeeze down on thetwo underlying plies II and Ile, the air car- 4 ried by those portionsof the surface' I4* under the cord groups is squeezed or pumpedlaterally into the newly formed grooves 20 which are nlled up with thisair and through which it may escape longitudinally of the belt. Anotherfactor causing the air to be drawn intothe grooves 20 is that when theyare formed thereis a tendency to create a vacuum at these groove pointsso that the unequal air pressure causes the air on the under surface torush into the grooves. In a sense the air may be said to be sucked fromthey surfaces under the cord groups as the grooves 2li are formed.

The ability of the belt to adapt itself to the contour of the pulley andits ability to prevent the formation of an air cushion between itselfand the pulley promotes and increases the tractive eiliciency withbenencial results. More power will be transmitted with less loss. Alsothe life of the belt will be prolonged since the wear will be equalizedwith the outer belt portions 'bearing their time of the vload along withtime. portions contacting theltop of the crown.

Although the foregoing description has set forth one form or belt, itwill be understoodv belt and arranged in a series of spaced groupsacrosssubstantially the full width of said belt, the space between said groupsbeing of substantially less width than ,the width of said groups, a websupporting saidL groups of cords. andan elastic bonding material in saidspace and joinlng said cords and said supporting web together 76 cords,said bonding material being formed with a groove in one surfaceparallelto said cords and being at on its other surface, whereby anormally at pulley contacting surface is formed in which e longitudinalair relief groove is created under the first mentioned groove duringoperation of the belt over s pulley.

2. A power transmission belt comprising a nlurality of cords extendinglongitudinally of said belt and arranged in a series of spaced groupsacross substantially the full width of said belt, the space between saidgroups `oeing of substantially less widthtthan the Width of said groups,an elastic bonding material in said space yand joining the cordstogether while permitting iirnited relative longitudinal and transversemovement between said groups of cords, said bonding material beingformed with a groove in one surface parallel to the cords and being flaton its other surface, and a fabric cover enclosing and following thecontour of lthe aforementioned elements, whereby a normally not pulleycontasting surface is formed in lwhich a longitudinal air relief grooveis created under the rst mentioned groove during operation of the beltover a pulley.

3. A power transmission belt comprising a plu-A aforementioned elements,whereby a normally hat pulley contacting surface is formed in which alongitudinal air relief groove is created under the rst mentioned grooveduring operation of the belt over a pulley.

t. A power transmission belt comprising a.

plurality of cords extending longitudinally of said belt and arranged ina series of spaced groups across substantially the full width of saidbelt, the space between said groups being of substantially less widththan the width of said groups, e, web supporting said groups of cords,an elastic bonding material in said space and joining said cords andsaid supporting web together while permitting limited relativelongitudinal and transverse movement between said groups of cords, saidbonding material being formed with a groove in one Surface parallel toseid cords and being nat on its other surface, and a fabric coversurrounding and following the contour of the aforementioned elements,whereby a noily fiat contacting pulley surface is formed in which a.longitudinal air relief groove is created under the first mentionedgroove during operation of the belt over a pulley.

- DELEVAN F. MORGAN.

soy

